Channel loss and cable design

[G8YU]

I have a PS Audio Stellar Gain Cell and M700 monoblocks.

Everything was great until I turned it on recently and noticed the right channel was at whisper level and would not increase. I could hear a soft thump in the right channel with each increment of the volume knob. I checked the channel balance; and found it was set to the middle, and altering it didn't help.

I tried muting and unmuting, unplugging everything; but nothing brought the right channel back. I began checking all connections and inspecting cables. I then discovered the XLR cables between the SGC and M700 monos were mismatched as seen in the photo.



The cable with hollow pins is for the right channel amp. I got these from Ivan. He had them sent direct from the manufacturer.

I took the SGC over to a different system for testing. I discovered that a digital coax input will activate the left and right XLR or RCA outputs. A XLR input, as the only source, will activate the left and right XLR outputs; but I'm not certain they sounded equal in volume. If a RCA input is added, the right channel is only at whisper level. In my system I use all the analog inputs and some of the digital inputs.

I installed an Arcam integrated amp for use as a preamplifier in place of the SGC; and both channels are working well from any input source.

Has anyone had experience with an RCA input failure like this? Could the one unconventional XLR cable have caused electrical damage?

The Stellar Gain Cell will be four years old in April; so whether it was damaged or just failed, it's past the warranty length.

[clpetersen]

It is not the cables. The 'hollow' pins are a red herring so to speak. The RCA input anomaly is an important clue. It may be an issue with the balanced input circuit in the SGA. The signal seems to be getting subtracted off somehow, why the output is near zero.


Contacted PS Audio??

[G8YU]

Here's what happened with my lost channel problem.
I did some further diagnosis to ensure I was certain of exactly what was broken.
I contacted PS Audio, who had me send the Stellar Gain Cell to them for repair.
They took excellent care of me by covering the repair under warranty and returning it to me.
They said that they replaced a couple chips in the SGC. It's back in the Stereo now sounding as good as ever.
I also got some new XLR cables, which gave a rather significant improvement; but that's a story for another thread.

[clpetersen]

Glad to hear they took care of you!